1. Field of the Invention
The present invention relates to 3D-conversion of a map, and in particular, to a system, method, and computer program for automatically converting 2D map data into a 3D map.
This application is based on Japanese Patent Application No. Hei 11-1454, the contents of which are incorporated herein by reference.
2. Description of the Related Art
A conventional system for 3D conversion is disclosed in Japanese Patent Application, First Publication No. Hei 10-111882. This 3D converter system comprises: a data reader for reading out 2D CAD data produced by a 2D CAD system; a figure assignor for assigning the extracted figures in at least two reference planes in a triaxial reference system; a outermost line extractor for extracting the outermost lines of the figures in the reference planes; a solid body producer for producing a solid body by expanding the outermost lines in the directions of the normal lines with respect to the reference planes; and a solid body synthesizer for producing 3D CAD data by synthesizing the solid bodies based on the 2D CAD data. This technique remarkably reduces the time required for production of the 3D CAD drawing from the 2D CAD drawing, and simplifies the input operation by a CAD operator.
Another conventional 3D converter system is disclosed in Japanese Patent Application, First Publication No. Hei 9-331440. This 3D converter system comprises: a projective transformation producer for producing projective transformations which associate coordinates in each 2D image with projective coordinates in a plane; a depth value producer for producing depth values representing distances between an imaging device and targets, based on the normalized projective transformation and on the projective coordinates of the targets of the 2D images; and a 3D coordinate producer for providing 3D scene information by producing 3D Euclidean coordinates of the targets, according to an equation with respect to 3D Euclidean coordinate axes in the reference plane or to the 3D Euclidean coordinate of the reference position, based on the projective transformation coordinates of the reference position and the target point and on the depth value of the target point. According to this conventional technique, when producing another 3D scene from a different point of view based on the same 2D image, an accurate 3D scene is obtained without the correction of the parameters for the imaging device.
However, in the above conventional techniques, the height data which is absent must be manually input or must be compensated with other 2D data. That is, the 3D data cannot be automatically obtained only from the 2D data which represents points on a map. Further, the data size of the stored 3D map data is increased because the 3D data requires more coordinate data than the 2D data.
As another conventional technique, Japanese Patent Application, First Publication No. Hei 4-149681 discloses a method for producing 3D data from the 2D image data and height information. Japanese Patent Application, First Publication No. Hei 4-293078 discloses a method for producing a 3D model from 2D contour map data by calculating heights from the 2D contour map. Japanese Patent Application, First Publication No. Hei 10-283501 discloses a method for detecting a building based on colors on the map read by a scanner.
Further, Japanese Patent Application, First Publication No. 9-54544 discloses a map display device which comprises a storage means for storing coordinates forming the flat shape of an object with height information, and a processor for producing a 3D image from the coordinates and the height information.
While the above conventional techniques produce the 3D image, these devices require the additional information such as the height information, which is not part of the existing data and must be additionally input. Further, the additional information increases the data size of the 3D image.
It is therefore an object of the present invention to provide a system, method, and computer program for automatically converting 2D map data into a 3D map, which reduces the data size of the 3D map data, and naturally makes use of the existing hierarchical 2D map data to produce the 3D map data.
In a first aspect of the present invention, the map 3D-converter system for converting 2D maps into a 3D map, comprises: a 2D map data storage device for storing 2D map data with an attribute indicating that the 2D map data includes horizontal positions of the top view, or vertical positions of a side view; a 3D conversion instructor for specifying an identification value for identifying a target map and a reference position for developing the target map in a 3D space; a 3D converter for converting the 2D map data, read from the 2D map data storage device, into 3D map data, based on the identification value and the reference position specified by the 3D conversion instructor; and a 3D map data storage device for storing the 3D map data produced by the 3D converter.
In a second aspect of the present invention, in the invention presented in the first aspect, the 2D map data is associated with other 2D map data in a lower class in the 2D map data storage device.
In a third aspect of the present invention, in the invention presented in the first aspect, the 3D conversion instructor instructs the number of lower classes to be developed by the 3D conversion process.
In a fourth aspect of the present invention, the invention presented in the first aspect further comprises a 3D map data display for displaying 3D map data stored in the 3D map data storage device.
In a fifth aspect of the present invention, in the invention presented in the first aspect, the 3D conversion instructor comprises a device for receiving a 3D conversion request from a user, and the 3D converter converts the 2D map data into the 3D map data, based on the 3D conversion request input to the 3D conversion instructor.
In a sixth aspect of the present invention, a method is provided for converting 2D map data into a 3D map, comprising the steps of: storing 2D map data with an attribute indicating that the 2D map data includes horizontal positions of the top view, or vertical positions of a side view; specifying an identification value for identifying a target map and a reference position for developing the target map in a 3D space; converting the 2D map data into 3D map data, based on the identification value and the reference position; and storing the 3D map data in a 3D map data storage device.
In a seventh aspect of the present invention, in the invention presented in the sixth aspect, the stored 2D map data is associated with another 2D map data in a lower class.
In an eighth aspect of the present invention, the invention presented in the sixth aspect further comprises the step of instructing the number of lower classes to be developed by the 3D conversion process.
In a ninth aspect of the present invention, the invention presented in the sixth aspect further comprises a step of displaying 3D map data stored in the 3D map data storage device.
In a tenth aspect of the present invention, the invention presented in the sixth aspect further comprises steps of: receiving a 3D conversion request from a user; and repeating conversion of the 2D map data into the 3D map data, based on the input 3D conversion request.
In an eleventh aspect of the present invention, the program instructions in the computer readable medium perform: storing 2D map data with an attribute indicating that the 2D map data includes horizontal positions of the top view, or vertical positions of a side view; specifying an identification value for identifying a target map and a reference position for developing the target map in a 3D space; converting the 2D map data into 3D map data, based on the identification value and the reference position; and storing the 3D map data in a 3D map data storage device.
In a twelfth aspect of the present invention, in the invention presented in the eleventh aspect, the stored 2D map data is associated with another 2D map data in the lower class.
In a thirteenth aspect of the present invention, in the invention presented in the eleventh aspect, the program instructions include instructions for instructing the number of lower classes to be developed by the 3D conversion process.
In a fourteenth aspect of the present invention, in the invention presented in the eleventh aspect, the program instructions include instructions for displaying 3D map data stored in the 3D map data storage device.
In a fifteenth aspect of the present invention, in the invention presented in the eleventh aspect, the program instructions include instructions for: receiving a 3D conversion request from a user; and repeating conversion of the 2D map data into the 3D map data, based on the input 3D conversion request.
According to the present invention, because, based on the request sent from the 3D conversion instructor, only necessary data are read from the 2D map data storage device, and the 3D converter 22 performs the 3D conversion based on the information from the 2D map attribute data storage device. Thus, the 2D data, which represent the points on the map in the specified area, are automatically converted into the 3D data.
Because the coordinate data, which are used to produce the 3D map data, are stored as the 2D values in the 2D map data storage device, the map 3D conversion system advantageously reduces the data size for the 3D map information.
Because the data are read from the 2D map data storage device, and the 3D converter 22 performs the 3D conversion based on the information from the 2D map attribute data storage device, even the 2D map management system, which has the hierarchy structure associating a map with another map, naturally makes use of the existing hierarchical 2D map data to produce the 3D map data.
Because the invention avoids the display of an unnecessary map which is not requested by the user, the user easily reaches the target detailed map.
The process of the present invention is fast because the 3D conversion for unnecessary maps is avoided.